How DRM differs from KGI?

olafBuddenhagen at olafBuddenhagen at
Tue Aug 30 22:49:39 PDT 2011


On Thu, Jun 23, 2011 at 11:04:30PM +0530, PRASANNA KUMAR wrote:

> I came across something called as KGI - kernel graphics interface
> ( It seems it provides the same features
> as KMS. What is the difference between those two?

Well, KMS is actually an extension of the DRM; together they handle all
aspects of the graphics hardware access -- which is indeed very similar
to what KGI intended to do. (And it's kinda fun watching KMS developers
reinvent various ideas that were already present in KGI one by one :-) )

> Any specific reason for not choosing KGI?

Several. Generally speaking, KGI did too much. Rather than just graphics
hardware drivers, they also reinvented the whole input and console
systems along the way -- not as patches against the existing code base,
but as a completely new code base written from scratch. Obviously, Linus
didn't like that.

On the application side, they weren't very cooperative either: XGGI (X
server adapted to work with KGI) was basically a fork of XFree86, and
for all I know they never even *tried* discussing the ideas with
upstream. Also their drivers were written from scratch (with some major
overengineering applied there) -- unlike the KMS drivers, which are
somewhat adopted ports of the preexisting and usually quite mature X

To sum up, the KGI folks mostly had the right ideas more than a decade
earlier -- but they totally failed to present them in a viable form :-(


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